Systems and methods for monitoring a patient

ABSTRACT

A system for monitoring a patient includes an inflatable cuff configured to at least partially occlude an artery of the patient, and a sensor configured to determine a first parameter associated with the at least partially occluded artery and to generate an output signal indicative of the first parameter. The system also includes a processor configured to receive the output signal and information indicative of an occlusion efficiency of the cuff. The processor is configured to determine a hemodynamic parameter of the patient based on the output signal and the information.

TECHNICAL FIELD

This application is directed to systems and methods for monitoring apatient, and in particular, to systems and methods for determining ahemodynamic parameter of a patient.

BACKGROUND

Traditional non-invasive blood pressure monitoring devices operate byinflating a blood pressure cuff to a pressure above a patient's systolicblood pressure. Because the systolic pressure is usually not know priorto inflation, the cuff must be inflated to such a pressure to ensurethat the patient's arterial blood flow is completely occluded. Onceabove systole, pressure data collected during inflation and/or deflationof the cuff is used to determine systolic and diastolic pressures of thepatient.

Typically, automated non-invasive blood pressure devices have a fixedcalibration to determine the pressure a cuff is applying to a limb of apatient, based on an input signal from a pressure sensor. The size,type, and/or configuration of the cuff being used, however, mayintroduce variation with respect to the pressure measured by the sensorversus the actual pressure a cuff is applying to a limb. Even thoughsuch variations in cuff designs or configuration may have a relativelysmall effect on the resulting blood pressure measurement (typicallybetween approximately 0 mmHg and approximately 5 mmHg), such variationsare large enough to cause difficulties in satisfying applicable bloodpressure cuff regulations.

The systems and methods described herein are directed toward overcomingthe difficulties described above.

SUMMARY

In an exemplary embodiment of the present disclosure, a system formonitoring a patient includes an inflatable cuff configured to at leastpartially occlude an artery of the patient, and a sensor configured todetermine a first parameter associated with the at least partiallyoccluded artery and to generate an output signal indicative of the firstparameter. The system also includes a processor configured to receivethe output signal and information indicative of an occlusion efficiencyof the cuff. The processor is configured to determine a hemodynamicparameter of the patient based on the output signal and the information.

In a further exemplary embodiment of the present disclosure, a method ofdetermining a hemodynamic parameter of a patient includes inflating acuff to an occlusion pressure, wherein inflating the cuff at leastpartially occludes an artery of the patient. The method also includesdetermining a parameter associated with the at least partially occludedartery and receiving information indicative of an occlusion efficiencyof the cuff. The method further includes determining the hemodynamicparameter of the patient based on the parameter and the information.

In another exemplary embodiment of the present disclosure, a method ofdetermining a hemodynamic parameter of a patient includes determining atleast one of a systolic pressure, a diastolic pressure, and a meanarterial pressure associated with an artery at least partially occludedby a cuff. The method also includes determining an occlusion efficiencyof the cuff based on at least one of a size, type, and model of thecuff. The method further includes determining a hemodynamic parameter ofthe patient based on the at least one of the systolic pressure, thediastolic pressure, and the mean arterial pressure, and the occlusionefficiency of the cuff.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system according to an exemplary embodiment of thepresent disclosure.

FIG. 2 shows a flow chart illustrating an exemplary method of thepresent disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates a monitoring system 10 according to an exemplaryembodiment of the present disclosure. System 10 can be configured tomonitor a patient 14, and in some embodiments, to determine ahemodynamic parameter of the patient 14. System 10 can include a cuff 12configured to at least to partially occlude the movement of bloodthrough a vessel, vein, and/or artery 22 of the patient 14. In someembodiments, cuff 12 can be configured to completely occlude an artery22 of patient 14, and the artery 22 may be, for example, the brachialartery. For example, the cuff 12 may be inflated to any known occlusionpressure, and at such an occlusion pressure, the artery 22 may be atleast partially occluded. Although shown in FIG. 1 as surrounding theupper arm of patient 14, cuff 12 may be adapted for placement on anysuitable part of patient 14, including, for example, a wrist, a finger,an upper thigh, or an ankle. In addition, one or more cuffs 12 could beplaced at different locations about and/or on patient 14 for use withsystem 10.

The exemplary cuffs 12 of the present disclosure may be formed from anymedically approved material known in the art. Such materials may behighly flexible, durable, and suitable for contact with, for example,the skin of the patient 14. Such materials may also be tear-resistant,fluid-impermeable, and recyclable. Such materials may include, forexample, paper, cloth, mesh and/or polymers such as polypropylene orpolyethylene. In still further exemplary embodiments, such materials maybe coated and/or otherwise treated with one or more additives that causethe material to become biodegradable within a desired time interval(e.g., within 2 to 3 months). Each of the exemplary cuffs 12 describedherein may have a respective length, width, and inflated height suitablefor use with a particular patient 14. For example, a first cuff 12intended to be used with an adolescent patient 14 may have a firstdeflated length and a first deflated width, and a second cuff 12intended for use with an adult patient 14 may have a correspondingsecond deflated length and second deflated width. In such an exemplaryembodiment, the first deflated length may be less than the seconddeflated length and the first deflated width may be less than the seconddeflated width. Unless otherwise indicated, the lengths and widthsreferred to for the duration of this disclosure are intended to bedeflated lengths and widths. In exemplary embodiments, inflated lengthsand widths of the exemplary cuffs described herein may be different thanthe corresponding deflated lengths and widths.

The cuff 12 may include one or more bladders (not shown) or other likeinflatable devices. Such a bladder may be formed from a single piece ofmaterial or, alternatively, from two or more pieces of material that arejoined together through heat sealing, ultrasonic or RF welding,adhering, and/or other like processes. In still further exemplaryembodiments, the cuff 12 may form one or more inflatable pockets thatperform the same functions as a bladder. In such exemplary embodiments,the bladder may be omitted. It is understood that the cuff 12 and/orbladder may be inflatable to an occlusion pressure of approximately 160mm Hg or greater to assist in at least partially occluding the artery22. In exemplary embodiments, the cuff 12 may include one or more ports(not shown) fluidly connected to the internal pocket or bladder toassist with inflation and/or deflation thereof.

The pressure or volume of fluid within cuff 12 may be controlled by acuff controller 16 operably associated with the cuff 12. Cuff controller16 can include a pump or similar device to inflate and/or deflate thecuff 12. For example, cuff controller 16 could supply cuff 12 with afluid such as air to increase the pressure or volume within the cuff 12.In other embodiments, cuff controller 16 could include mechanical,electrical, or chemical devices configured to control occlusion of theartery 22 via cuff 12. The cuff controller 16 may be mechanically,fluidly, and/or operably connectable to one or more of the portsdescribed herein to assist in inflating and/or deflating the cuff 12.

In some embodiments, cuff controller 16 can generally maintain cuff 12at about a target or reference pressure. For example, once a target orreference pressure has been chosen, cuff controller 16 could inflate andmaintain the cuff 12 to the target or reference pressure. While thepresent disclosure refers to a target or reference pressure, it shouldbe understood that the actual pressure applied by cuff 12 may varyslightly from the target or reference. For example, the actual pressureapplied to patient 14 may generally remain within appropriate limits,such as, for example, within 2%, 5%, 10%, or 20% of the target orreference pressure. This difference between the chosen target orreference pressure and the actual pressure applied by the cuff 12 may becaused by the occlusion efficiency of the respective cuff 12. A cuff's“occlusion efficiency” may be defined as the ease or difficulty withwhich air pressure within the cuff 12 is transferred to force on theunderlying artery 22. For example, cuffs 12 having a higher occlusionefficiency may be capable of applying a relatively greater force to suchan artery 22 at a given inflation pressure than a like cuff 12 having arelatively lower occlusion efficiency. Prior to use, automatednon-invasive blood pressure monitoring devices are typically calibratedbased on a standard occlusion efficiency associated with the cuff typeto be used for blood pressure measurement. While such calibration iseffective when the appropriate cuff type is used with the monitoringdevice, such calibration is problematic when clinicians or other healthcare professionals use cuffs of a different type or design, and thushaving different occlusion efficiencies, with the blood pressuremonitoring device. Such calibration can also be problematic when theproper cuff-type is used if the cuff has a different occlusionefficiency than that used to calibrate the monitoring device.

System 10 can further include a sensor 18 configured to receive a signalassociated with the patient 14. In each of the exemplary embodimentsdescribed herein, the sensor 18 may determine one or more parametersassociated with an at least partially occluded artery 22 of the patient14. Such parameters may include, for example, a systolic pressure, adiastolic pressure, a mean arterial pressure, and/or other knownparameters associated with the cuff 12, the artery 22, and/or thepatient 14. As will be described in greater detail below, in furtherexemplary embodiments the sensor 18 may be configured to determine oneor more of an oscillation signal strength, an ambient temperature, ahumidity, a cumulative cycle count of the cuff 12, a volume of the cuff12, an occlusion pressure of the cuff 12, a cumulative time associatedwith the cuff 12 being inflated to a reference volume and/or pressure,and/or other like parameters. In exemplary embodiments, the referencepressure may be approximately 100 mm Hg, and the target pressure may beequal to the reference pressure. The reference volume may be any volumeof the cuff 12 and/or the bladder associated with reaching such areference pressure. The sensor 18 may comprise devices including, butnot limited to, one or more of a pressure sensor, a thermometer, athermocouple, a hygrometer, and/or a timer. The sensor 18 may be locatedat positions including, but not limited to, within, on, or about cuff12. System 10 may further include a plurality of sensors 18, and mayinclude a high-resolution sensor or pneumatic sensor designed to operatein conjunction with cuff 12.

In some embodiments, the sensor 18 can be configured to receive a signalassociated with an at least partially occluded artery 22 of patient 14.Such an input signal can arise from blood movement through a partiallyoccluded artery 22 or from a signal associated with an occluded bloodvessel. Sensor 18 could sample various aspects or characteristics of theartery 22 multiple times at various intervals. In additional exemplaryembodiments, sensor 18 could provide an indication of blood vesselmovement, such as, for example, oscillations arising from vascularexpansion or contraction. Such oscillations may produce a signal that isdetected by the sensor 18, and the strength of such an oscillationsignal may be used to determine a hemodynamic parameter of the patient14. For example, sensor 18 could be configured to detect an occlusionpressure or volume of cuff 12 that may vary periodically with the cyclicexpansion and contraction of the artery 22 of patient 14.

In additional exemplary embodiments, the sensor 18 may be configured toread, scan, sense, detect, and/or otherwise input information associatedwith the cuff 12. Such information may include, for example, anocclusion efficiency that is particular to the actual cuff 12 beingused, or an occlusion efficiency associated with the type, size, design,model, and/or style of cuff 12 being used. It is understood that thetype, size, design, model, and/or style of the cuff 12 may be parametersthat are unique or particular to the actual cuff 12 being used. Forexample, such parameters may include and/or may be indicative of thelength, width, inflated height, and/or other dimensions of the cuff 12,the shape of the cuff 12, the number of bladders included in the cuff12, the length, width, and/or inflated height of such bladders, themaximum inflated volume of the cuff 12, materials used to construct thecuff 12, and whether the cuff 12 is intended for use with a child,adolescent, adult, elderly, and/or bariatric patient 14, among otherthings. In such exemplary embodiments, the sensor 18 may comprise anRFID reader, a barcode reader, an MICR reader, a conductance sensor, aresistance sensor, a magnetic sensor, and/or any other like readingdevice known in the art. Such a sensor 18 may be configured to sense,scan, detect, and/or otherwise read information carried by one or moreinformation features 26 associated with the cuff 12. In addition tostandard text, such information features 26 may comprise one of an RFIDtag, a barcode, MICR printing, a conductive, resistive, and/or magneticstrip of material, and/or other known means for providing information.For example, such information features 26 may communicate an occlusionefficiency of the cuff 12 to the sensor 18 and/or to a user of thesystem 10. Such information features 26 may also communicate anidentification parameter particular to the cuff 12. Such anidentification parameter may be indicative of, for example, the type,size, design, model, and/or style of the cuff 12 being used. Such anidentification parameter may also comprise, for example, a serialnumber, a model number, a part number, and/or any other like informationenabling the particular cuff 12 to be identified for purposes oftracking or recording, for example, a cumulative cycle count, an age ofthe cuff, and/or any of the other parameters described herein.

One or more such information features 26 may be disposed on an outerexposed surface of the cuff 12 for reading by the sensor 18 or,alternatively, may be embedded within and/or formed integrally with thecuff 12. The sensor 18 may further comprise one or more cameras, scopes,optical devices, and/or other like components configured to readinformation from the information feature 26. In such exemplaryembodiments, the sensor 18 and/or components of the system 10 incommunication with the sensor 18 may employ various pattern recognitionsoftware, identification software, and/or other like controlhardware/software to assist in reading the information provided by theinformation feature 26. In such embodiments, the information feature 26may include text, characters, numerals, figures, and/or other indiciathat is screen printed, encoded, and/or otherwise viewable on a surfacethereof. Alternatively, such indicia may be printed, encoded, and/orotherwise disposed on a viewable surface of the cuff 12. Sensor 18 canfurther be configured to generate one or more output signals indicativeof each respective parameter that is determined. The output signal maybe generated based on an input signal received from patient 14. In oneaspect, the output signal can include a representation of an inputsignal associated with cuff 12 and/or patient 14.

One or more of the parameters determined by the sensor 18 may be used todetermine one or more hemodynamic parameters of the patient 14. Asdescribed herein, a hemodynamic parameter can include any indication ofcardiac or vascular health, such as, for example, an indication ofcardiac, circulatory, or vascular functionality. Specifically, ahemodynamic parameter can include a heart rate, a blood pressure, avessel compliance, an aortic index, an augmentation index, a reflectedwave ratio, and/or an indication of treatment. Such a blood pressure caninclude systolic pressure, diastolic pressure, and/or mean arterialpressure, and vessel compliance may include, for example, arterialstiffness. An indication of treatment can include a parameter reflectingthe effect of a drug treatment, or one or more treatments of a diseasestate.

In some embodiments, a hemodynamic parameter can be determined based ona suprasystolic measurement. In other embodiments, a hemodynamicparameter can be determined based on a first set of data obtained duringinflation of cuff 12 and a second set of data obtained during generalmaintenance of cuff 12 at about a target or reference pressure. Such atarget or reference pressure may be, for example, an occlusion pressurewherein the artery 22 is at least partially occluded. The first orsecond sets of data can include various data associated with a signalwaveform associated with patient 14 and/or cuff 12, and may includeoscillation signal strength, amplitude, frequency, morphology, feature,or mathematically derived data. Data may be derived from a derivative,integration, or frequency analysis, such as, for example, a fast-Fouriertransform. Data may also be derived from various algorithms, includingcurve fitting, a neural network, filtering, smoothing, or dataprocessing. It is understood that the system 10 may comprise any knownoscillometric or auscultation system, and that the system 10 may beconfigured to perform and/or otherwise employ any known oscillometric orauscultation methods.

Cuff 12, cuff controller 16, and sensor 18 may be operably associatedwith a cuff control module 20. Specifically, cuff control module 20could include one or more processors 28 configured to control one ormore operations of cuff 12, cuff controller 16, and/or sensor 18. Forexample, cuff control module 20 can control inflation and/or deflationof cuff 12 via control of cuff controller 16. The cuff control module 20and/or one or more of the processors 28 associated therewith may beconfigured to, for example, receive the output signals generated by thesensor 18. The cuff control module 20 and/or the one or more processors28 may also be configured to receive information, from the sensor 18and/or from an operator of the system 10, indicative of the occlusionefficiency of the cuff. In an exemplary embodiment, such information maybe sent to the cuff control module 20 by the sensor 18 as one or more ofthe output signals described above. The cuff control module 20 and/orthe one or more processors 28 may be configured to determine ahemodynamic parameter of the patient 14 based on, for example, an outputsignal of the sensor 18 and/or the information indicative of occlusionefficiency.

In some embodiments, cuff control module 20 can calculate a targetpressure. This calculation may be based on an output signal from sensor18, as described above. Cuff control module 20 may also controlinflation of cuff 12, inflation of cuff 12 to the target pressure, orgenerally maintaining inflation of cuff 12 at about the target pressure.For example, the cuff control module 20 could calculate a targetpressure during inflation of cuff 12. Such a calculation could take lessthan about 15 seconds. Cuff control module 20 could then generallymaintain cuff 12 at about the target pressure for a defined time period,such as, for example, less than about 10 seconds. In other embodiments,the target pressure could be generally maintained for a defined numberof cardiac cycles, such as, for example, six, eight, or ten cycles. Suchcardiac cycle data may be available upon reaching the target pressure.

In an exemplary embodiment, the cuff control module 20 and/or the one ormore processors 28 thereof may include a signal analysis module 30configured to analyze one or more signals received from the sensor 18and/or other inputs. For example, the signal analysis module 30 caninclude one or more filters configured to filter a signal associatedwith sensor 18 or cuff control module 20. Such filters can includeband-pass, high-pass, or low-pass filters. In such exemplaryembodiments, the signal analysis module 30 may assist in determining thehemodynamic parameter of the patient 14.

As shown in FIG. 1, the system 10 can further include a communicationmodule 24 configured to provide communication to patient 14 or one ormore operators. For example, communication module 24 could include adisplay configured to display one or more hemodynamic parameters. Inother embodiments, communication module 24 could include a wireless orother known transmitter configured to transmit data to a remotelocation. Communication module 24 may further include audio output tocommunicate with patient 14 and/or an operator of system 10.

In addition to the components outlined above, system 10 may includevarious other components as required, such as, for example, a memory, apower source, and a user input device. One or more components describedherein may be combined or may be separate and operate with wireless orwired communication links. Moreover, the various components of system 10could be integrated into a single processing unit or may operate asseparate processors 28. For example, the cuff control module 20,processor 28, sensor 18, communication module 24, and/or signal analysismodule 30 described herein may be disposed within a single housing, andsuch a housing may be configured for handheld use. In operation, one ormore processors 28 can be configured to operate in conjunction with oneor more software programs to provide the functionality of system 10.

As shown in the exemplary flow chart 100 illustrated in FIG. 2, methodsof monitoring the patient 14 and/or determining a hemodynamic parameterof the patient 14 may include determining one or more parametersassociated with the artery 22 as well as an occlusion efficiency of thecuff 12 being used. Such method may comprise oscillometric methods,auscultation methods, and/or any other patient monitoring methods. Forexample, such methods may include determining a parameter of the patient(Step: 102). Such a parameter may include, for example, at least one ofa systolic pressure, a diastolic pressure, and a mean arterial pressureassociated with the artery 22 while the artery 22 is at least partiallyoccluded by the cuff 12. Such methods may also include determining anocclusion efficiency of the cuff (Step: 104), and such an occlusionefficiency may be particular to the cuff 12 being used. For instance,such an occlusion efficiency may be based on at least one of the size,type, and model of the cuff 12. Such methods may further includedetermining a hemodynamic parameter of the patient 14 based on theparameter and the occlusion efficiency (Step: 106). It is understoodthat the various method steps described herein, and illustrated inexemplary FIG. 2, may be performed in any desirable order. The variousaspects of such exemplary methods will be described in greater detailbelow.

In exemplary methods of using the monitoring system 10, the occlusionefficiency associated with the cuff 12 may be determined in any numberof ways. For example, the occlusion efficiency may be determined throughclinical testing in which a number of blood pressure measurements orother like measurements are taken using the cuff 12 and the sensor 18.These measurements may then be compared to corresponding measurementstaken using a reference cuff of the same type, size, design, model,and/or style, but known to have a near perfect occlusion efficiency. Theocclusion efficiency of such a reference cuff may have a negligibleeffect on the blood pressure measurements taken with the reference cuff.In such an exemplary embodiment, the occlusion efficiency of the cuff 12may be based on a difference between a pressure applied by the referencecuff when the reference cuff is inflated to a target or referencepressure, and a pressure applied by the cuff 12 to, for example, an atleast partially occluded artery 22, when the cuff 12 is inflated to thesame target or reference pressure. Such a difference may result in ameasurement offset that is particular to the cuff 12. This offset may berecorded and/or otherwise permanently associated with the cuff 12, andthis unique offset may be used as a correction factor by the system 10when the cuff 12 is used for future measurements.

In other exemplary embodiments, the occlusion efficiency of the cuff 12may be determined through a series of bench tests using the cuff 12 anda pressure testing apparatus. Such an apparatus may include, forexample, a structure shaped like a limb of a patient 14 and equippedwith one or more sensors configured to detect the pressure applied tothe limb-shaped structure. In such exemplary embodiments, the cuff 12may be disposed about the structure, and may be inflated to a target orreference pressure. The sensors associated with the limb-shapedstructure may determine the actual pressure applied by the cuff 12, andthis actual pressure may be compared to the reference pressure. Adifference between these two pressures may result in a measurementoffset that is particular to the cuff 12. As described above, thisoffset may be recorded and/or otherwise permanently associated with thecuff 12, and this unique offset may be used as a correction factor bythe system 10 when the cuff 12 is used for future measurements. Suchoffsets may be one way of quantifying the occlusion efficiency used indetermining a hemodynamic parameter of the patient 14. In otherexemplary embodiments, these or other performance metrics associatedwith the cuff 12 may be used to quantify the occlusion efficiency. Forexample, percentages, functions, and/or other like metrics may also beused to quantify the occlusion efficiency offsets described herein.

In exemplary embodiments, the unique occlusion efficiency of the cuff 12may be used to modify and/or otherwise correct a hemodynamic parameterdetermination made using the system 10. In such embodiments, theocclusion efficiency may be combined with any of the parametersdescribed above to affect such a determination. It is understood thatsuch a combination may be performed through the use of one or moreequations, algorithms, control functions, and/or other means. In suchexemplary embodiments, the cuff 12 may be inflated to an occlusionpressure, and inflating the cuff 12 to the occlusion pressure may atleast partially occlude an artery 22 of the patient 14. The sensor 18may then determine one or more parameters associated with the at leastpartially occluded artery 22. An output signal indicative of the one ormore parameters may then be sent by the sensor 18 to the cuff controlmodule 20 for use in determining the hemodynamic parameter. The cuffcontrol module 20 may also receive information indicative of theocclusion efficiency of the cuff 12. Such information may be receivedfrom the sensor 18 in the form of an additional output signal.Alternatively, such information may be received from a user enteringsuch information into the cuff control module 20 via one or moreoperator input devices. In still another exemplary embodiment, theunique occlusion efficiency of the cuff 12 may be stored within a memoryof the cuff control module 20. Such a stored occlusion efficiency may beretrieved from memory by the cuff control module 20 in response toreceiving, for example, information including and/or based on anidentification parameter particular to the cuff 12. Such a storedocclusion efficiency may also be retrieved from the memory based oninformation including the type, size, design, model, and/or style of thecuff 12 being used. In further exemplary embodiments, the cuff controlmodule 20 may prohibit use of the system 10 if the occlusion efficiencyof the cuff 12 cannot be retrieved, is not entered properly, and/or isotherwise unknown. For example, the cuff control module 20 may prohibita hemodynamic parameter determination or operation, such as by disablingthe cuff controller 16, the sensor 18, and/or the cuff 12, in responseto a failure to enter the occlusion efficiency or an incorrect occlusionefficiency entry.

Once the occlusion efficiency has been retrieved or properly entered bythe user, one or more algorithms may utilize the occlusion efficiencyparticular to the cuff 12 in determining a blood pressure or otherhemodynamic parameter of the patient 14. In additional exemplaryembodiments, one or more algorithms may utilize the occlusion efficiencyin combination with one or more empirically derived variables indetermining the hemodynamic parameter. In such exemplary embodiments,the variable may be, for example, a scaling factor derived based on testdata and/or other information associated with the cuff 12 or based onpredefined ranges of other parameters such as, for example, systolic anddiastolic estimates or the time to inflate the cuff 12. Such a variablemay, for example, be derived based on the occlusion efficiency of thecuff 12. In such exemplary embodiments, the variable may scale and/orotherwise affect the hemodynamic parameter determination based on theocclusion efficiency of the cuff 12. For example, when using a firstcuff known to be less efficient than a like second cuff, the system 10may calculate the hemodynamic parameter using the occlusion efficiencyin combination with a relatively large variable. Such a relatively largevariable may result in a correspondingly large adjustment in thedetermined hemodynamic parameter.

In still further exemplary embodiments, information received by the cuffcontrol module 20 from the sensor 18 and/or from the operator may beindicative of the occlusion efficiency of the cuff 12 as well as one ormore additional parameters. For example, the information received by thecuff control module 20 may be based on the occlusion efficiency and atleast one of the empirically derived variable, a cumulative timeassociated with inflating the cuff 12 to a reference volume, a volume ofthe cuff 12 at the occlusion pressure, a surface area of contact betweenthe cuff 12 at the occlusion pressure and the patient 14, and a valueindicative of the size of the cuff 12. For example, a unique numericvalue may be associated with each cuff 12 depending on the shape,volume, dimensions, and/or other characteristics thereof.

In further exemplary embodiments, the information received by the cuffcontrol module 20 may be based on the occlusion efficiency, anempirically derived variable, and at least one of a numeric valueindicative of the tone, muscularity, fat content, and/or othercharacteristics of an arm of the patient 14, a strength of a pulse orother oscillation signal sensed by the sensor 18 during occlusion of theartery 22, an ambient temperature of the environment in which the cuff12 is used, a humidity of the environment in which the cuff 12 is used,a cumulative use and/or cycle count of the cuff 12, a metric and/orother numeric value associated with an arterial stiffness of the patient14, an age of the patient 14, a deflated surface area of a bladderassociated with the cuff 12, and an age of the cuff 12. In suchexemplary embodiments, the occlusion efficiency specific and/orparticular to the respective cuff 12 being used may be combined with anyof the parameters described above to affect a hemodynamic parameterdetermination. Such parameters may also generally be referred to as, forexample, “first parameters,” “arterial parameters,” “cuff parameters,”and/or “patient parameters.” As described above, such a combination maybe performed through the use of one or more equations, algorithms,control functions, and/or other means utilizing these parameters asinputs. In such exemplary embodiments, the empirically derived variablemay be used as a scaling factor to increase the accuracy of thehemodynamic parameter determination.

It is understood that by using the occlusion efficiency of the cuff 12,as well as the other information, parameters, and/or variables discussedabove, in determining a hemodynamic parameter of a patient 14, theaccuracy of such determinations may be improved. For example, themethods described herein may reduce the error associated with suchhemodynamic parameter determinations such that applicable medical deviceregulations may be satisfied. As known systems are not configured toutilize an occlusion efficiency that is unique to the cuff indetermining a hemodynamic parameter of a patient, the systems andmethods described herein are more accurate and more reliable thanexisting systems.

Other embodiments of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the disclosure contained herein. For example, in additional exemplaryembodiments, the system 10 may comprise any known automated or manualauscultation system. In such exemplary embodiments, the system 10 mayfurther include one or more microphones or other like sound sensorsconfigured to sense and/or otherwise detect auscultation signalsassociated with the artery 22. Accordingly, the methods described hereinmay be employed by either an oscillometric system or an auscultationsystem. It is intended that the specification and examples be consideredas exemplary only, with a true scope and spirit of the presentdisclosure being indicated by the following claims.

What is claimed is:
 1. A system for monitoring a patient, comprising: aninflatable cuff configured to at least partially occlude an artery ofthe patient; a sensor configured to determine a first parameterassociated with the at least partially occluded artery and to generatean output signal indicative of the first parameter; and a processorconfigured to receive the output signal and information indicative of anocclusion efficiency of the cuff, and to determine a hemodynamicparameter of the patient based on the output signal and the information.2. The system of claim 1, wherein the first parameter comprises one of asystolic pressure, a diastolic pressure, and a mean arterial pressure.3. The system of claim 1, wherein the hemodynamic parameter comprisesone of a heart rate, a blood pressure, and an arterial stiffness.
 4. Thesystem of claim 1, wherein the sensor comprises a pressure sensor. 5.The system of claim 1, wherein the occlusion efficiency is based on adifference between a pressure applied by a reference cuff when thereference cuff is inflated to a reference pressure, and a pressureapplied by the cuff when the cuff is inflated to the reference pressure.6. The system of claim 1, wherein the sensor and the processor aredisposed within a single housing.
 7. The system of claim 1, wherein thecuff further comprises an information feature communicating theocclusion efficiency of the cuff.
 8. A method of determining ahemodynamic parameter of a patient, comprising: inflating a cuff to anocclusion pressure, wherein inflating the cuff at least partiallyoccludes an artery of the patient; determining a parameter associatedwith the at least partially occluded artery; receiving informationindicative of an occlusion efficiency of the cuff; and determining thehemodynamic parameter of the patient based on the parameter and theinformation.
 9. The method of claim 8, wherein the hemodynamic parameteris determined based on the occlusion efficiency of the cuff, theparameter, and an empirically derived variable, and wherein the variableis derived based on the occlusion efficiency of the cuff.
 10. The methodof claim 8, wherein the received information is based on the occlusionefficiency and a cumulative time associated with the cuff being inflatedto a reference pressure.
 11. The method of claim 8, wherein the receivedinformation is based on the occlusion efficiency and a surface area ofcontact between the cuff at the occlusion pressure and the patient. 12.The method of claim 8, wherein the received information is based on theocclusion efficiency and a value indicative of a cuff size.
 13. Themethod of claim 8, wherein the received information is based on theocclusion efficiency and a value indicative of at least one of an armtone of the patient, an oscillation signal strength, an ambienttemperature, a humidity, a cumulative cycle count of the cuff, anarterial stiffness of the patient, an age of the patient, a deflatedsurface area of a bladder associated with the cuff, a cuff size, and anage of the cuff.
 14. The method of claim 8, wherein the hemodynamicparameter comprises one of a heart rate, a blood pressure, and anarterial stiffness.
 15. The method of claim 8, wherein the occlusionefficiency is based on a difference between a pressure applied by areference cuff when the reference cuff is inflated to a referencepressure, and a pressure applied to the at least partially occludedartery by the cuff when the cuff is inflated to the reference pressure.16. The method of claim 8, wherein the information is based on anidentification parameter particular to the cuff.
 17. A method ofdetermining a hemodynamic parameter of a patient, comprising:determining at least one of a systolic pressure, a diastolic pressure,and a mean arterial pressure associated with an artery at leastpartially occluded by a cuff; determining an occlusion efficiency of thecuff based on at least one of a size, type, and model of the cuff, anddetermining a hemodynamic parameter of the patient based on the at leastone of the systolic pressure, the diastolic pressure, and the meanarterial pressure, and the occlusion efficiency of the cuff.
 18. Themethod of claim 17, further including receiving an input indicative ofthe occlusion efficiency.
 19. The method of claim 17, wherein thehemodynamic parameter is calculated based on an empirically derivedvariable, and wherein the variable is derived based on the occlusionefficiency of the cuff.
 20. The method of claim 17, wherein thehemodynamic parameter is calculated based on a value indicative of atleast one of an arm tone of the patient, an oscillation signal strength,an ambient temperature, a humidity, a cumulative cycle count of thecuff, an arterial stiffness of the patient, an age of the patient, adeflated surface area of a bladder associated with the cuff, a cuffsize, and an age of the cuff.
 21. The method of claim 17, wherein thehemodynamic parameter is blood pressure.
 22. The method of claim 17,wherein the hemodynamic parameter is arterial stiffness.
 23. The methodof claim 17, wherein the occlusion efficiency is based on a differencebetween a pressure applied by a reference cuff when the reference cuffis inflated to a reference pressure, and a pressure applied by the cuffwhen the cuff is inflated to the reference pressure.
 24. The method ofclaim 17, further including prohibiting determination of the hemodynamicparameter in response to an incorrect occlusion efficiency entry.